We're excited to share our research into that: https://blog.mutinywallet.com/fixing-payment-reliability/

We built our own internal platform for measuring payment success rates through a bunch of trail and error, with many configuration tweaks along the way. We store the results of that so that we may revisit what increased reliability.

If you have an interest in payments on LN or are building on LDK, we'd highly recommend you take a read and learn from many of the problems we've faced and how we've solved them. If we can be of any help to others, please reach out if you're seeing similar issues.

Please let us know if things improve. It's not going to eliminate payment failures by any means, but it should be greatly improved from where we've been at. We'll monitor things as we go and continue to make improvements now that we can quantify reliability.